According to Shing-Fat Fred Ma: > Thanks for your explanations, Grant. Though some it raises > more questions, in case you or anyone else care to elaborate. > > Grant McDorman wrote: > > > -depth does not control the connection depth; instead, it tells the viewer > > to try to create its local window at that depth *with the default visual*. > > I thought the whole point of specifying the veiwer depth was to > reduce bandwidth. Why would one want to reduce the viewer > depth without also having it reflected in the communication? > For the thin client model, the (naively) reasonable thing to do > is to get server to quantize each color plane to the coarseness > requested by the viewer depth. Obviously something I'm > missing here.
Viewer depth is to adapt the viewer to the local machine (that is, the machine on which the viewer is displaying). It is *not* to control bandwidth, although it may affect that as a side effect. Options which control the viewer display are -depth, -truecolour, -owncmap, and -fullscreen (and the standard Xt option -display). Conversely, the bandwidth control options are -encodings and -bgr233 (and, for TightVNC, -compresslevel and -quality). The viewer will force -bgr233 if the remote system - the VNC server - is TrueColour and the local system is 8-bit (pseudo-colour). > > What is happening in your case is that your local system's default visual is > > 8-bit pseudo colour, and a 24-bit pseudo-colour visual doesn't exist; the > > viewer, in that case, will use the only available pseudo-colour visual > > (8-bit) and behave as if the -bgr233 command line option was supplied. > > This would certainly explain the "truant" viewer behaviour, > though I was under the impression that the display is *not* > pseudocolor unless the server is started with "-cc 3". I ran > into a problem with CAD tools for IC layout because it wanted > a pseudocolor visual, and someone on the VNC list rightly > suggested that the "-cc 3" was required. I'm assuming that > "visual" is a property of the server display only, in particular > the display created by vncserver. Here I am talking about the local display, not the VNC server. The VNC viewer can display using TrueColour if the local display supports it; however, if it is not the default you have to tell the viewer explictly to use it. One must remember that, in this case, there are *two* X servers involved: the VNC (virtual) server and the physical X server (presumably XSun) that you use to run the viewer. In order to run and view an application in TrueColour, *both* must support TrueColour. If either is 8-bit, then you will get an 8-bit palette of some form. The vncviewer -truecolour and -depth 24 options can be used to view *any* VNC server configuration; i.e. you can view an 8-bit PseudoColour, or an 8, 16, or 24 bit TrueColour VNC server. To further clarify: Most X servers, including the VNC server, will only support a single visual (and depth) at one time. Some, including the Sun X server, will support multiple simultaneous visuals; one of these will be the default visual. The VNC viewer '-depth' and '-truecolour' options are only useful when it is displaying on a (client) X server like this that have multiple visuals and/or depths. > > If the server has a true colour visual available, this command line should > > do what you want: > > vncviewer -depth 24 -truecolour _server_:_num_ > > Just something I want to clarify here. By server, I presume > you mean vncserver rather than host machine for the vncserver? > Because for VNC, it seems that server and display and visual > are all one and the same. A server cannot have more than 1 > display, some being true color while others are not. Assuming > they are synonymous, then it seems the existence of "-cc 3" > and "-truecolour" specify the same thing, except one is on the > server side and the other is on the viewer side....right? No, sorry. This, again, is the viewing machine (a Sun machine, if I recall correctly). -truecolour has no effect on the VNC server whatsoever. "server" here was "local X server" (or $DISPLAY where the VNC viewer is run). -- Grant McDorman <[EMAIL PROTECTED]>, Sr. Software Design Consultant Cedara Software Corp. <URL:http://www.cedara.com> (formerly I.S.G. Technologies Inc.) Mississauga, Ontario, Canada [demime 0.99c.8 removed an attachment of type application/pgp-signature] _______________________________________________ VNC-List mailing list [EMAIL PROTECTED] http://www.realvnc.com/mailman/listinfo/vnc-list
